FIGURE 1.

Pathological changes of the central airways in chronic obstructive pulmonary disease. a) A central bronchus from the lung of a cigarette smoker with normal pulmonary function. Only small amounts of bronchial smooth muscle are present and the epithelial glands are small. b) In contrast, a subject with chronic bronchitis has bronchial smooth muscle that appears as a thick bundle and enlarged bronchial glands. c) The enlarged bronchial glands at a higher magnification. A chronic inflammatory process involving polymorphonuclear leukocytes (arrowhead) and mononuclear cells, including plasma cells (arrows) can also be seen. Reproduced from [11], with permission from the publisher.